Field evaluations of grouted roof bolts.
New technology for longwall ground control. Proceedings: U.S. Bureau of Mines Technology Transfer Seminar. Mark C, Tuchman RJ, Repsher RC, Simon CL, eds. Pittsburgh, PA: U.S. Bureau of Mines, 1994 Aug; :91-101
Three field tests were conducted by the U.S. Bureau of Mines (USBM) to study the support-rock interaction mechanics of fully grouted roof bolts. Thirty-two instrumented, fully grounted bolts were installed in three different longwall gate roads to measure load changes at various stages of the mining process. Readings were taken during section development and, for sites 1 and 2, as each longwall face passed the test sections. These studies provided several valuable insights into the behavior of fully grounted resin bolts. In every case, the bolt loads resulting from entry development were greater than what would be produced from simple suspension of the immediate mine roof. As far-field stresses induced by mining activity were transferred to the rock surrounding the entry, the bolts responded by increasing in load. Many sections of the resin-grouted bolts yielded, but none of the bolts came close to the strain necessary to cause failure. The degree of loading seemed to be related to geology and stress fields; i.e., where roofs were weaker and there was more overburden, bolt loads were higher. This type of instrumented support could be used to monitor problem areas, evaluate loading conditions in the immediate roof with respect to bolt reinforcement and other mining activities, and improve the design selection process for rock reinforcement, resulting in significant improvements in underground mine safety.
Longwall-mining; Mining-industry; Ground-control; Ground-stability; Geology; Computer-software; Computer-models
Mark-C; Tuchman-RJ; Repsher-RC; Simon-CL
New technology for longwall ground control. Proceedings: U.S. Bureau of Mines Technology Transfer Seminar.